During the testing of some new drugs, it is necessary to monitor the heart of a patient being treated with the new drug. It is inconvenient for an active patient to be kept in a controlled environment, such as a hospital, during the monitoring. Consequently, patients have been provided with heart monitoring equipment which they may take home with them. Such equipment comprises means for detecting an electrocardiographic (ECG) signal and a device for transmitting the detected signals through the public telephone network. If a patient begins to feel unwell or detects an abnormality in his heartbeat, he must dial a central station and instruct an operator, at the central station, to prepare to record a transmitted ECG signal. This system suffers from a number of disadvantages including the problem of language, since drug trials often take place across national boundaries, the non-availability of telephones and poor quality telephone lines. Also, drug companies are wary of becoming directly involved in patient care which is properly the domain of the patient's physician.
The aforementioned disadvantages may be overcome by replacing the telephone link by data storage media which may be posted to the central station. One known device is the CardioRam produced by Elmed Elektromedizinische Gerate. However, this device records ECG signals for a 24 hour period which makes it unsuitable for drug testing methodologies where intermittent recording is employed over extended periods, e.g. a month.
Another device is known from European Patent Application No. 346685 which is capable of intermittent recording of ECG signals.
None of the prior art IC card ambulatory heart monitoring apparatuses are entirely suitable for the purpose of apparatus embodying the present invention. It is intended that patients will use such apparatus unsupervised. This leads to the problem of ensuring that the patients use the apparatus properly and that the apparatus itself is functioning correctly.
It is an aim of the present invention to provide an ambulatory heart monitoring apparatus which is simple enough to meet the market demand at a reasonable cost, whilst providing high quality information on heart function.